Fit, comfort and cushioning are desired features in footwear. Inflatable bladders have been used in articles of footwear, or shoes, to provide improved fit and cushioning for better comfort. The inflatable bladder may form part of either the shoe upper or the sole of a shoe and may be inflated by a variety of inflation mechanisms, including a detachable inflation device, an on-board inflation device, an automatic underfoot inflation device, etc.
One goal in developing inflatable bladders for shoes has been to control the volume and pressure of air within the bladder. Too little air or too little air pressure within an inflatable bladder may not provide sufficient fit and/or cushioning to the shoe, such that the shoe may be loose or may not provide adequate cushioning. Too much air or too high of air pressure within an inflatable bladder may cause the bladder to pinch or exert painful pressure to areas of the foot during athletic activity. Thus, various deflation mechanisms and pressure regulators have been provided to control the air pressure within the inflatable bladder.
U.S. Pat. No. 6,785,985 and Published U.S. Patent Application Numbers 2004/0003517 and 2005/0028404, each of which is incorporated by reference herein in its entirety, describe, inter alia, various deflation mechanisms for controlling the amount of air within an inflatable bladder.
Another goal in shoe design is to provide an article of footwear with a low profile. As such, large and cumbersome features extending from an exterior surface of a shoe add weight to the shoe and are generally less aesthetically pleasing to the eye. Further, extending features may become hit, brushed against or damaged and may be hazardous to other participants during athletic activity, for example contact sports.
Another goal in designing shoe parts is ease of use. Inflation or deflation mechanisms which are difficult to use are not desirable.